Placing Dimensions Using the Select Reference Dialog Box
The Select Reference dialog box allows you to select the point on the model to which you want to attach a driven or reference dimension. It contains the following commands:
• 
—Allows you to select an entity. The dimension is attached to the reference at the pick point.
• 
—Allows you to select a surface.
• 
—Allows you to select an entity or surface.
• 
—Allows you to select the center of an arc or circle. The dimension is attached to the center of an arc or circle.
• 
—Allows you to select a midpoint of an edge or entity. The dimension is attached to the midpoint of the selected entity.
• 
—Allows you to select an intersection defined by two objects. The dimension is attached to the closest intersection point of two selected entities.
• 
—Allows you select two points or vertices and draws an imaginary line between the selected points or vertices. The imaginary line can be used as a dimension reference.
• 
—Allows you to select a point or vertex and draws an imaginary horizontal line through the selected point or vertex. The imaginary line can be used as a dimension reference.
• 
—Allows you to select a point or vertex and draws an imaginary vertical line through the selected point or vertex. The imaginary line can be used as a dimension reference.
| You can change the attachment type in the middle of creating a dimension. For example, you can select one point as on entity (  ), then change to center (  ) and select another point. |